I had an extra 10 minutes this AM and used it to compile weights and measurements of every B Fat (aka 27.5") tire I have in stock.

Weights:

Gnarwhal 4.5" = 1550g
Gnarwhal 4.0" = 1410g
Barbagazi 4.5 = 1347g
Hodag 3.8" = 1332g
Dillinger 4 = 1440g
Dillinger 5 = 1517g
D4 stud 60tpi = 1698g
D5 stud 120tpi = 1623g
Cake Eater 4.0 = 1353g
CE 4.5 stud = 1660g
Gnar 4.0 stud = 1463g
Gnar 4.5 stud = 1660g
FBF 3.8 EXO = 1490g
FBR 3.8 EXO = 1381g


Flat bead to bead:

Gnarwhal 4.5" = 245mm
Gnarwhal 4.0" = 210mm
Barbagazi 4.5 = 255mm
Hodag 3.8" = 210mm
Dillinger 4 = 230mm
Dillinger 5 = 241mm
Cake Eater 4.0 = 217mm
Cake Eater 4.5 = 260mm
FBF 3.8 EXO = 210mm
FBR 3.8 EXO = 210mm

Caveat emptor: All weights were measured on the same scale, all widths using the same spoke ruler. I don't purport that they are precise to the millimeter or the gram, merely that they are consistent.